Uses of `-moz-appearance: none` are changed to `appearance: none`.
Uses of other values that are simply reverting the appearance back to
its default are changed to `appearance: auto`.
Uses of values in UA sheets that are defining the inherent appearance of
widgets are changed to:
appearance: auto;
-moz-default-appearance: <value>;
since those values are either no longer supported on (-moz-)appearance,
or are still supported but only in some limited form.
There are some uses of `-moz-appearance: textfield` on <input
type=number> elements that are renamed to `appearance: textfield`.
Differential Revision: https://phabricator.services.mozilla.com/D83430
34d3b448a7